Memory cards are certified empty by the elections workers and poll workers before the election starts. Like multiple times up to that morning right before the polls open.

Of course if you open up a machine and replace the memory card it will show whatever you put on the card.

But for this to work a person would have to swap the cards in the machines after they are checked- so you would have to walk up to the machine with a screwdriver, start taking it apart, swap parts while poll workers are there watching with nobody noticing, and somehow do it without disturbing the tamper seal over the port for the card.

How, exactly, do you think they could pull that off.

Stupid video is only convincing to people who don't understand how simple technology works and how elections work. Anyone with a clue about either is smart enough to see it proves nothing.